When these rhythms are part of a 24-hour cycle, as the preceding examples are, they are called circadian rhythms. The brain controls and helps maintain the internal “clock” for these rhythms.

External factors can influence biological rhythms. For instance, exposure to sunlight and drugs such as caffeine can affect sleep schedules.

What Are Biological Rhythm Disorders?

When natural biological rhythms are disturbed, disorders can occur. Common disorders are:

sleep disorders (such as insomnia)

jet lag

mood disorders (such as depression
and seasonal affective disorder)

shift-work disorders

How Are Biological Rhythm Disorders Treated?

Treatments for biological rhythm disorders vary greatly and depend on the underlying cause. For example, the effects of jet lag are usually temporary, so it is not treated medically. In cases of shift-work disorder or mood disorders, lifestyle changes may help. However, some effects, such as fatigue and decreased mental sharpness, are difficult to alleviate (Price, 2011).

For people who live in places with short winter days, using a light box can help with seasonal affective disorder.

While the body can adapt to interruptions of biological rhythms, such as the day (awake), night (sleep) schedule being reversed, health complications such as digestive issues sometimes arise. People who work night shifts may have an increased risk for certain kinds of cancer (JNCI, 2011) and other life-threatening conditions.

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